Lubricating oil composition



tates atent 3,065,178 Patented Nov. 26, 1962 tice This invention relates to an improved lubricating oil. More, particularly, the present invention relates to a lubricating oil composition of improved stability which comprises a major proportion of a lubricating oil, and synergistic amounts of a compound selected from the group consisting of orthoalkylated phenols and phenyl-alphanaphthylamines in combination with highly basic magnesium sulfonates.

It has now been found and this finding forms the basis of the present invention, that the use of highly basic magnesium sulfonates in combination With an orthoalkylated phenol or a phenyl-alpha-naphthylamine in lubricating oils imparts surprising and unexpectedly improved oxidation stability to the lubricating oil fraction.

The lubricating oil compositions of the present invention are extremely useful as lubricants for internal combustion engines because of their outstanding oxidation stability at high temperatures. While the lubricants of this invention may be used to lubricate any type of internal combustion engine they are particularly important as crankcase lubricants for railway diesel locomotives since this particular type of diesel engine is designed to operate at rather high temperatures, especially under high load conditions.

The lubricating oil fraction employed in the practice of the present invention will preferably be a mineral lubricating oil of coastal or Mid-Continent origin. For example, the mineral lubricating oil base stock may be derived from Gulf Coastal, Panhandle, Pennsylvania, or California type crude oil. The lubricating oil fraction will preferably have a viscosity index in the range of 50400 and a viscosity at 100 F. in the range of 800 1200 SSU. While the lubricating oil fraction is preferably a mineral lubricating oil, other lubricating oils may be employed in the composition of the present invention. Thus, lubricating oils produced synthetically by polymerizing olefins and/ or esters to oils of the proper molecular weight and having the lubricating oil characteristics and viscosity ranges indicated may be used.

and 2,4,6 tri-tertiary butyl phenol. The alkyl groups of the orthoalkylated phenol will preferably contain about -1 to 6 carbon atoms. The 4,4-methylene bis-(2,6 di-tertiary butyl phenol) is particularly preferred in the preparation of the lubricating oil compositions of this invention.

Phenyl-alpha-naphthylamine is well known in the prior art and has been used in various lubricating oil compositions as an anti-oxidant. Phenyl-alpha-naphthylamiue and its preparation are disclosed in U.S. Patent 1,988,299.

The magnesium sulfonates useful in the present invention will be highly basic and have a total base number in the range of 100 to 400. The total base number is abbreviated TBN and is determined by standard potentiometric methods in accordance with ASTM D-664 test procedure. These highly basic magnesium sulfonates are available commercially and are known as Bryton 7560B, 9076-A, 9199-A, 9200-A, etc. This type of highly basic magnesium sulfonate is normally prepared by treat ing a conventional magnesium sulfonate with magnesia and carbon dioxide.

The finished lubricating oil composition will contain in the range of 80 to 98 vol. percent of the lubricating oil fraction, 2 to 20 vol. percent of the highly basic magnesium sulfonate and 0.2 to 1.0 wt. percent, based on the total weight of the above composition, of an ortl1oalkylated phenol or phenyl-alpha-naphthylamine.

Other additives such as polymeric viscosity index improvers, pour point depressants, and anti-foaming amounts of silicone fluids may be added if desired.

EXAMPLE I In order to further illustrate the present invention, a number of compositions were made up in accordance with the present invention in which synergistic amounts of the orthoalkylated phenol and phenyl-alpha-naphthylamines were combined with the highly basic magnesium sulfonates. 'These compositions were compared with other compositions employing the orthoalkylated phenol and phenyl-alpha-naphthylamine in combination with various alkaline earth metal sulfonates.

Table 1 illustrates the various sulfonates, A through E,

'used in the preparation of the lubricating oil compositions of this invention and the sulfonates, F through I, used in the comparative formulations. The highly basic magnesium sulfonates of this invention were purchased from Bryton and the highly basic calcium sulfonates were purchased from Lubrizol Corp.

Table I RAILROAD DIESEL LUBRICANTS-HIGH ALKALINITY SULFONATES Over- Percent Percent Percent Percent 'Iypebased 1 TBN 2 CO3 Ash 8 Ca Mg with- Sultonate of invention:

Mg sullonate 4 Mg Mg sulfonate 4 (30%).- Mg Mg sulfonate 4 (30%).- Mg Mg sulfonate 4 (30%)" Mg Mg sulfonate 4 (30%) Mg Ca sultonate -l 29 10. 4 2.9 Ca sulfonate (45%).-.- Ca 127 6.2 21.5 6.2 Ca sulfouate 4 (45%) Mg 75 3.3 14 1. 7 1. 7 Ca. sulfonate 5 (45%) 0a 275 1 By adding excess Ca or Mg oxide and treating with C02. 2 Total vase number (ASTM D-664).

B Sulfated.

4 These Ca and Mg sultonates were purchased from Bryton. 6 This Ca sulfonate was purchased from Lubrizol Corp. as Lubrizol 56.

The orthoalkylated phenol is preferably an orthoalkylated phenol such as 2,6 di-tertiary-butyl phenol, 2,6 ditertiary-Z-dimethylamine para-cresol, 4,4-methylene bis- (2,6 di-tertiary butyl phenol), ortho-tertiary butyl phenol,

sulfonate-phenol combination of this invention. Table II Large increases in torque indicate severe Wear while small also illustrates the improved results obtained with magincreases in the torque readings indicate slight Wear. nesium sulfonates over both neutral and high alkalinity All the lubricants of this invention and the comparaoalcium sulfonates. tive formulations were prepared with a hydrofined, phenol The several blends were subjected to an E.R.E. stabilextracted coastal distillate (boiling between 340 and ity test which comprises heating the lubricant to 340 F. 700 F. at mm. mercury pressure), having a viscosity in the presence of a Cu-Pb bearing and a silver strip and index of 63, as the lubricating oil fraction. The formumeasuring the viscosity increase in terms of Sayboit seclations were prepared by simple admixture of the additives onds Universal after 19 and 23 hours. This test is used with the above lubricating oil base.

Table II OXIDATION STABILITY AND SILVER LUBRIOIIY Lubricant composition ERE stability test Vis. Sulfonate SSU Vis. inc. SSU/ Cu-Pb bearing Three disc Phenol at 100 100 F. atweight loss in silver wear weight F. mg. attest rating Vol. percent Type a percent 19 hrs. 23 hrs. 19 hrs. 23 hrs.

Lubricants of invention: V

A 5.0 0. a 39 50 0 1 Good-fair. A 10.0 0. 8 33 0 1 Good. A 5.0 0. 2 34 55 3 8 A 10.0 0.2 26 1 2 B 5.0 0.8 24 55 2 4 Fair. B 10.0 0. 8 28 52 2 4 Do. B 15.0 0. 8 89 4 5 Do. 0 5.0 0. 8 20 24 0 0 Good. 0 10.0 0. 8 35 44 0 0 Do. 0 15.0 0.8 30 39 0 0 Do. D 5.0 0.8 28 33 0 1 Fair. D 10.0 0. 8 20 25 0 0 Good. D 15.0 0.8 21 2e 0 0 Fair-poor.

F 5.0 0.8 75 250 Excellent G 5.0 0. 8 1,170 352 993 31 127 Poor. G 10.0 0. 8 1,177 97 296 5 9 Very poor. H 5.0 0. 8 1,172 520 839 145 303 Good. H 10.0 0.8 1,189 473 947 71 181 Poor. I 10.0 0.8 929 51 194' 0 0 Good.

1 Base stock-63VI undewaxed, severely hydroflned and phenol extracted coastal distillate. 1 The phenol is 4,4-1nethylene bis-(2,6 (ii-tertiary butyl phenol). 3 Relates to designation given in Table I above.

to determine the stability of the lubricant to oxidation as Table III shows the synergistic oxidation stability obshown by the viscosity increase as well as the lubricants tained by the combination of sulfonates with an orthoalcorrosiveness to silver-steel and copper-lead bearings. kylated phenol and particularly the unexpected improve- The three disc silver wear test is a laboratory test develment in oxidation stability obtained when the sulfonate is oped to measure the silver wear prevention characteristics 45 a highly basic magnesium sulfonate, as illustrated by of railroad diesel lubricants when silver is used as a bearlubricants 28 through 30.

Table III Lubricant composition 1 ERE lubricating stability test (23 hrs. at 340 1 Vis. SSU Three disc Lubricant Sull'onate Phenol at 100F. Vis. inc. Cu-Pb Silver silver wear weight SSU at bearing weight test rating percent 100 F weight lossinmg. Type 3 Vol. lossin mg.

percent 5. 0 0.0 920 1, 004 189 0 5 Good. 7.5 0.0 955 1,371 200 0 5 Do. 10. 0 0. 0 995 1, 055 110 0. 5 Do. 0. 0 0. 8 1,151 318 156 1. 5 Do. 0. 0 0. 25 709 313 144 a. 9 5. 0 0. 2 931 8 0 2 7.5 0. 2 955 7a 1 0. 4 10. 0 0. 2 1, 004 36 2 1 Base stock-68 VI undewaxed. severely hydrofined and phenol extracted coastal distillate. The phenol is 4,4'-methylene bis-(2,6 (ii-tertiary butyl phenol). 3 Relates to designation given in Table I above.

ing surface for steel. The results obtained in this test Table IV illustrates the overall performance in aChevare important since about of all railway diesel rolet L-4 engine test of a lubricating oil composition of engines use a silver-on-steel surfaced bearing. The test this invention as compared with similar experimental and consists of rotating a steel ball at 600 r.p.m. on three stacommercial lubricating oil compositions. Lubricant 32 tionary silver discs under a constantly applied load of 10 of Table IV is representative of the lubricating oil comkg..in-the presence of the test lubricant at 150 C. Torque positions of this invention while lubricants 33, 34 and 35 is measured after one minute of operation and every two represent comparative compositions. minutes thereafter, up to a total test time of 15 minutes. The Chevrolet L-4 engine test is well known in the art and uses a standard 6-cylinder Chevrolet engine fitted with copper-lead bearings. Here the engine was run conobtained in Table III for the phenol-magnesium sulfomates of this invention.

Table V Base Stock 1 plus ERE lubricant stability test Phenyl- Viscosity Viscosity Increase, Bearing Silver Mg sulioalpha- SSU at SSU at 100 F. atweight weight nate, vol. naph- 100 F. loss at 23 change at 23 percent thylarnine, hrs., mg. hrs., mg.

weight 19 hrs. 23 hrs. percent Ca sulfonate 4 vol. percent 1 63 V .I. undewaxed, severely hydrofined and phenol extracted coastal distillate having a viscosity at 210 F. of 60-80 SSU tinuously for 36 hours after which time the piston deposits and weight loss of the Cu-Pb hearings were measured and an inspection of the used lubricant was made. The Chevrolet L-4 engine test is important since it gives a good indication of the oils oxidation stability under actual operating conditions.

I Represents the weight loss in mg. of the copper-lead bearing.

1 Represents piston cleanliness based on visnalrating of0 to 100, 0 being (cicmpl%te1y covered with deposits and 100 being completely free of eposi s.

I Same as lubricant 2 of Table II.

I 93.75 vol. percent of base stock of Table II, 2.25 v01. percent of Ca-Ba nonyl phenol sulfide, 4.0 vol. percent of sulfonate F of Table I and 0.4 weight percent phcnyl-alpha-naphthylamine.

95.0 vol. percent of same base stock 0! Table II but 5.0 vol. percent of sulfonate F of Table I and 0.8 weight percent of 4,4 methylene bis- (2,6 di-tertiary butyl phenol).

The fact that synergistically improved oxidation stability can be obtained by combining the highly basic magnesium sulfonates of this invention with phenyl-alphanaphthylamine is shown in the following table. The improved oxidation stability obtained with the phenyl-alphanaphthylamine-magnesium sulfonate combination is com parable with the unexpected and surprising improvement In summary, Table I characterizes the highly basic magnesium sulfonates of this invention. Tables 11 through IV illustrate the surprising oxidation stability and wear resistance obtained by the combination of these highly basic magnesium sulfonates with an orthoalkylate-d phenol in a lubricating oil fraction. Table V shows that phenol-alpha-naphthylamine will also impart an unexpectedly high oxidation stability to the lubricating oil fraction when combined with the highly basic magnesium sulfonatcs of this invention.

Tables 11 and V are of particular importance since they show advantage for magnesium sulfonates over calcium sulfonates in the same base number range. They also show that a total base number in the range of 100 to 400 and preferably in the range of about 150 to 300 is preferred.

What is claimed is:

A lubricating oil composition consisting essentially of a hydrofined and phenol extracted mineral lubricating oil having a viscosity index of about 50 to about 100, and a synergistic combination with regard to oxidation inhibition of about 5 to 10 volume percent of a 30 wt. percent concentrate in mineral oil of a high basic magnesium sulfonate having a total base number about 375, and about 0.2 wt. percent of 4.4'-methylene bis-(2,6 ditertiary butyl phenol).

References Cited in the file of this patent UNITED STATES PATENTS 2,629,693 Barton et al Feb. 24, 1953 2,695,273 Hook et al Nov. 23, 1954 2,807,653 Filbey et al Sept. 24, 1957 2,856,359 Schlicht Oct. 14, 1958 2,895,913 Carlyle a a1. July 21, 1959 FOREIGN PATENTS 454,227 Canada Jan. 18, 1949 

